Wastewater quality

The collection, treatment and disposal of wastewater is important in protecting your health and our environment. We provide wastewater services throughout Western Australia and the Indian Ocean Territories (Christmas and Cocos Islands). As part of these services, we manage the daily treatment of more than 490 million litres of wastewater (more than 180 billion litres for the year), through 110 treatment plants across these regions and territories.

Products generated following the treatment process are either reused or safely disposed to the environment. Each recycling or disposal option requires a specific quality of water to meet environmental, public health or social expectations. There are 76 recycled water schemes, owned and operated by Water Corporation, local government or private industries, supplying recycled water for industrial reuse and irrigation of public open spaces and woodlots.

Managing our wastewater quality

To verify the quality of our treated wastewater products, we run an extensive wastewater quality monitoring program. We base our performance on more than 58,000 samples from wastewater treatment plants, disposal sites, recycling schemes and groundwater monitoring bores and over 196,600 individual analyses performed by individual laboratories.

We're committed to the safe and effective management of wastewater, recycled water, groundwater replenishment, biosolids and sludge, which is set out in our Wastewater Quality Policy. We work collaboratively with our Health Regulator to operate our wastewater services while protecting public health. Please see our Memorandum of Understanding on Wastewater Services and Groundwater Replenishment with Department of Health. Compliance with this was a new requirement of our Water Services Licence issued by the Economic Regulation Authority in May 2020.

In 2025, an independent review of our Wastewater Service and Groundwater Replenishment Performance found the Corporation had established and maintained effective mechanisms for managing its wastewater quality obligations through its Wastewater Quality Framework, including: 

• Established and maintained systems, processes and procedures of its wastewater catchment and biosolids & sludge management MoU obligations.
• Risks from commercial and industrial wastewater sources are appropriately reviewed and managed.
• Effective biosolids & sludge management systems and processes are established and maintained.
• Demonstration of a clear and consistent organisational commitment to maintaining high standards in wastewater quality.

The audit successfully identified opportunities for improvement that Water Corporation is addressing to ensure continual improvement of our Wastewater Services and Groundwater Replenishment MoU requirements.

How do we report on our performance?

Our Wastewater Quality Annual Report is specifically designed to provide the Department of Health, our customers and the Western Australian public, with information on wastewater services and how we manage metropolitan and regional wastewater and recycled water schemes to meet quality and health requirements.

We produce this report in line with the requirements of our Water Services Licence, and our Memorandum of Understanding for Wastewater Service and Groundwater Replenishment with Department of Health.

Download 2023-24 Annual Report